Aqua gun



FIG. 1 is a front, right perspective view of an aqua gun;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a back side view thereof;

FIG. 5 is a front side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines illustrate environmental structure and form no part of the claimed design. 

The ornamental design for an aqua gun, as shown and described. 